+1 I don't and have never used any audio output from my GPS. I do use my Sena to answer and make voice-dialed calls through my Android phone and use my iPod Touch to play/listen to music.

Of course, it doesn't help that my Zumo 660 has a known problem with its Bluetooth implementation (besides crappy audio fidelity) that makes it problematic to really use it paired with my phone and the Sena paired to it.